Before we dip into the world of the Oyster cap, let's check the basics. This year's average price rise is 2.5%, which TfL are describing as "frozen in real terms", but which you might still describe as "higher than my annual pay rise." Nevertheless it's lower that last year's 3.1%, and much lower than the 7% increase imposed two years previously.

Here are some of 2015'sfares in historical perspective, with Ken's years in red and Boris's in blue.

Cost of a single central London tube journey

2005

2006

2007

2008

2009

2010

2011

2012

2013

2014

2015

Oyster

£1.70

£1.50

£1.50

£1.50

£1.60

£1.80

£1.90

£2.00

£2.10

£2.20

£2.30

Cash

£2.00

£3.00

£4.00

£4.00

£4.00

£4.00

£4.00

£4.30

£4.50

£4.70

£4.80

The Zone 1 Oyster tube fare rises 4.5% in January to a new high of £2.30. Pessimists will note that this is 53% higher than when Boris came to power. Optimists, however, should note that it's still only 35% higher than a decade ago. Meanwhile anyone paying by cash continues to be screwed, as TfL try ever harder to persuade people to switch to plastic.

Cost of a tube journey from Green Park to Heathrow

2008

2009

2010

2011

2012

2013

2014

2015

Oyster (peak)

£3.50

£3.80

£4.20

£4.50

£4.80

£5.00

£5.00

£5.10

Oyster (off-peak)

£2.00

£2.20

£2.40

£2.70

£2.90

£3.00

£3.00

£3.10

Cash

£4.00

£4.00

£4.50

£5.00

£5.30

£5.50

£5.70

£6.00

All Oyster fares for London tube journeys outside Zone 1 are rising by 10p, which is a smaller percentage increase the further out you go. But paper ticket buyers heading to Heathrow get to stump up 30p more, indeed a Zone 1-6 ticket faces a bigger increase than any other cash single fare.

Meanwhile on the buses...

Cost of a single central London bus journey

2005

2006

2007

2008

2009

2010

2011

2012

2013

2014

2015

Oyster

80p

80p

£1

90p

£1

£1.20

£1.30

£1.35

£1.40

£1.45

£1.50

Cash

£1.20

£1.50

£2

£2

£2

£2

£2.20

£2.30

£2.40

£2.40

x

The pay-as-you-go bus fare rises by 3.4% in January, that's up 5p to £1.50. Over the last ten years it's roughly doubled, and as you'll see has increased every year since Boris came to power. Meanwhile the cash fare has of course vanished, leaving a few non-Oyster stragglers unable to travel - a problem which a brand new ticket aims to address.

The One Day Bus & Tram Pass will be a disposable Oyster card with £5 face value, usable for one day's travel only. It's not yet clear how it'll work, whether the clock starts ticking when you buy it or the first time you use it - I'd assume the latter. You'll then be able to travel on as many buses as you like up to 4.30am, so best not start using one at midnight or you'll be chucking money away. Indeed anyone who makes only one (or two) bus journeys on their One Day Pass will be doing precisely that, paying the equivalent of £5 (or £2.50) per ride, which is rather more than the £1.50 that an Oyster user would pay.

Cost of One Day Travelcard

Z1-2
anytime

Z1-4
anytime

Z1-6
anytime

Z1-6
offpeak

cost now

£9.00

£11.40

£17.00

£8.90

to be retained?

×

✔

✔

✔

cost in 2015

£12.00

£12.00

£17.00

£12.00

Meanwhile next year's fare announcement includes yet another nail in the coffin of the paper Travelcard. There used to be six of these (Z1-2, Z1-3, Z1-4, Z1-5, Z1-6 and Z2-6), but from January only the Z1-4 and Z1-6 options will remain, and at inflated prices. The latest to vanish is the Z1-2 travelcard, whose current users will need a Z1-4 instead - a fare increase of 33%. TfL don't care, they'd like to see visitors to the capital using Oyster rather than queuing in large numbers at ticket offices for a one-off rectangle of cardboard, and this expensive nudge might just do it.

Which brings us finally to the whopping decrease in this year's fare announcement - that of the daily Oyster price cap. They're impressive figures.

Oyster 'pay as you go' cap

Z1-2

Z1-3

Z1-4

Z1-5

Z1-6

Z1-9

cap now

£8.40

£10.60

£10.60

£15.80

£15.80

£19.60

cap in 2015

£6.40

£7.50

£9.20

£10.90

£11.70

£20.00

% change

-24%

-29%

-13%

-31%

-26%

+2%

And this is where the claims of massive savings for part-time workers have arisen. Anyone who doesn't travel enough days to make a weekly travelcard worthwhile can instead benefit from a much reduced daily cap, adjusted to equal one fifth of the weekly travelcard fare. The potential savings are vast, as much as £661 annually for a three day a week Z1-5 traveller. But don't think this is going to benefit every part-time worker, because it's not a saving for all - the cap only affects those who make several journeys a day.

Let's use the example of someone living in Edgware (Z5) who commutes to central London (Z1) in peak hours each day. The price of a single Z1-5 tube journey is currently £4.70, and to come home again the same, making a daily total of £9.40, which is well below the existing Oyster cap of £15.80. From January the cap tumbles to £10.90, but that's still above the return tube fare of £4.80×2 = £9.60, so no saving is made. Indeed nobody making one return tube journey a day will save a penny from this new arrangement, no matter how many days a week they travel.

Things are very different with an additional journey thrown in. Suppose our Edgware resident travels to the station every morning by bus, and home again the same way, adding an extra £1.45×2 = £2.90 to their daily fare. That makes a total of £12.30, still well below the cap at present, but not so in 2015. Next year the bus plus tube combination increases to £12.60, but this is now below the reduced £10.90 cap, leading to a daily saving of £1.70. For our part time worker this adds up to an annual £230 saving, nowhere near as good as the best case £661 scenario, but very welcome all the same.

And there are of course losers, because somebody has to fund all these price cap reductions. In this case the burden falls on Outer Londoners who travel a lot during the day or at weekends, because the offpeak Oyster cap is being scrapped.

Oyster 'pay as you go' cap (off-peak)

Z1-2

Z1-3

Z1-4

Z1-5

Z1-6

Z1-9

cap now

£7.00

£7.70

£7.70

£8.50

£8.50

£11.60

cap in 2015

£6.40

£7.50

£9.20

£10.90

£11.70

£20.00

% change

-9%

-3%

+19%

+28%

+38%

+72%

Those who travel only within zones 1 to 3 will see a reduction in the cap, paying no more after the third tube journey or fifth bus ride. But those further out will have to make more journeys before the cap kicks in, in Zone 6 the equivalent of three extra journeys. If you're used to whizzing around the outer reaches of the capital at weekends, or making lots of short journeys in the middle of the day, you might well be one of those paying a lot more.

And one last thing. Look at the final column of the table, for those using Oyster services in zones 7, 8 and 9 outside the Greater London boundary. They're not getting an Oyster cap reduction at all, they're getting a massive offpeak hike of 72%, so bad luck them. But that's the price you pay for not living in London - the Mayor can do what he likes with your fares, even though you don't directly elect him.